\begin{tikzpicture}
    \tkzDefPoints{0/0/A, 3/0/B, 2.5/2/C, 0.8/2/D}

    \tkzDrawPolygon(A,B,C,D)
    \tkzDrawSegment(B,D)
    \tkzLabelPoints[left](A,D)
    \tkzLabelPoints[right](B,C)
\end{tikzpicture}

